Thread cutter for sewing machines



Nov. 4, 1941.

H. HACKLANDER THREAD CUTTER FOR SEWING MACHINES File d Nov. 13, 1939 J/ans Meklander Patented Nov. 4, 1941 UNITE THREAD CUTTER FOR SEWING MACHINES Hans Hacklander, Linden, N. J., assignor to The Singer Manufacturing Company, Elizabeth, N. 3., a corporation of New Jersey Application November 13, 1939, Serial No. 303,945 4 9 Claims.

This invention relates to improvements in sewing machines, and more particularly to improvements in sewing machine thread-cutters adapted to sever the thread-chains connecting stitched articles, such as filled bags and the like The primary object of the present invention isthe provision of an improved thrad cutter of the type in questionwhich is effective to cut the thread-chain between stitched articles without stopping the sewing machine.

Another object of the invention is to provide a thread-cutter which is simple in construction,

v durable, and requiring sharpening at protracted periods only.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations, and arrangement of parts hereinafter set forth and illustrated in the accompanying drawing of a preferred embodiment of the invention, from which the several features of the invention; and the advantages attained thereby will be readily understood by those skilled in the art.

Referring to the drawing, Fig. 1 is a fragmenv 25 end an eccentric 26 secured to the main-shaft Iii.

tary rear perspective view of a portion of a sewing machine embodying the present invention;

showing the thread-cutter and the feedingme'chanism by which the thread-cutter is actuated.

Fig. 2 is a top plan view of the usual feed-bar and feed-dog with the boss on the feed-bar in' section showing the mounting of the" movable cutter-blade.

Fig. 3 is an elevational view of the stationary ledger blade, illustrating the way in which it is fastened to the machine-bed.

in Fig. 3 with the feed-bar and cloth-plate in section.

The present invent on, as illustrated in the drawing, is embodied in a; sewing machine having a. frame including a bed I from one end of which rises a bracket-arm 2 terminating in ahead 3 overhanging the bed. Journaled in-t he head 3 is the usual reciprocatory needle-bar 4 carrying :at its lower-end'a threaded needle 5, and a two-thread chain-stitches.

The articles to be stitched are adapted to be advanced past the stitching mechanism by means of a so-called four-motion feeding mechanism.

I The actuatingconnections for th'efeeding mech- 55 anism in the machine. illustrated are located beneath the level of the cloth-plate 8 and are driven by a rotary main-shaft l6 journaled in the bed i. The feeding mechanism comprises a feed-dog H 5 secured for limited vertical adjustment upon one end of a feed-bar I2, thefeed-dog projecting throughfeed-slots l3 in a throat-plate M fastened upon the cloth plate 8. ,At its rear end the feed-dog II is formed with an offset l5 which increases thewidth of the feeding surface of the fed-dog, the off-set on the feed-dog cooperating with a relatively vertically yieldable insert l6 on the presser-foot. I, thereby to more effectively chain oil between the articles stitched.

35 The feed-bar I? at its other end is pivotally connected tothe bifurcated upper end of a rocking frame I! journaled upon pintles I8, only one of which is shown, threaded into horizontal lugs laintegral with the bed I. Frictionally clamped by means of screws 20 upon the extended hub of the rocking frame I! is the lower split end of an upstanding rock-lever 2| longitudinally slotted, as at 22, to adjustably receive one end of an actuating pitman 23 embracing at its other pitman 23 in the slot 22 relative to the axis of oscillation of the rock-lever 2i.

Rising-and-falling movements of the feed-dog ii are derived from an eccentric 25 on the mainshaft Ill through the medium of the relatively 35 short vertically disposed pitman 2'6 pivotally con-. Fig. 4 is a, left end view of the parts represented nected at its upper end to the bifurcated end of the feed-bar l2,

The thread-cutter now to be described in detail comprises a stationary ledger-bladefl and a movable blade 28. I As clearly shown-in Figs 3 and 4, the stationary blade 21 at its lower end is preferably formed with ;a right-angle ear 29 apertured to receive the fastening screws 30 threaded into an upstanding boss 3] integral with 45 the bed I. Adjacent the upper 'end the stationary blade 21 is formed with a V- shapedthread-re- I ceiving' notch 32, theilower'edge 33 of which is preferably substantially horizontal 'anddisposed a little beneath the level of the cloth-plate 8,

" while the upper member 34 ispreferably inclined slightly upwardly and is sharpened to provide one cutting edge 34'. Cooperating with thisedge 34' is the sharpened edge 35 of the movable blade 28. The movable blade, as shown in Fig. 2, is supported by two horizontal pins 36 sewing machine.

biased into contact with the sharpened edge 34 of the stationary blade 21 by a coil-spring 88 disposed in an aperture formed in the boss 31.-

In order that the two blades will remain in cutting relation when they are separated to their fullest extent, the movable blade 28 is formed at one end ,of its cutting edge 35 with a guide or pilot 3!. To minimize re-sharpening of the two blades the upper member 34 is bent slightly to the left into a position out of alignment with th remainder of the stationary blade 21, see Flga'z and 4, and as the movable blade partakes of the movement of the feed-bar II, it cooperates with the cutting edge 34' of the stationary blade in true scissors action. That is to say there is but side thereof a thread-receiving notch opening in the direction of feed and having one side thereof sharpened to provide a cutting edge, a movable cutter-blade cooperating with the cutting edge of said stationary blade and supported by at least one pin arranged for endwise movement in said feed-bar, and means for yieldingly maintaining the blades in cutting relation with each other.

- vices, feeding mechanism including a feed-bar for point contact between the two cutting edges as the movable blade is actuated, the movable blade during its cutting action shifting laterally toward the feed-bar it in opposition to the coil-spring 3B under the influence of the bent upper member 36 v tionary blade 27, the upper member 34 thereof functioning as a guard-element to protect the work against contact with the movable cutting blade 28. In other words, the upper member 34 of the stationary blade 21 normally holds the work out of range of the movable blade 28 which is actuated continuously during the operation of the In order for the thread-cutter to become effective to sever the thread-chain between the stitched articles, the operator manually introduces the thread-chain into the V-shaped thread-receiving notch 32 while the machine is in operation. It is desirable to have the threadis specially designed to sever the thread-chain between stitched articles, such as filled bags and the like; which operates directly with the feeding mechanism of the sewing machine;- and which,

although continuously operating, is effective only when the operator desires it to be.

Having thus set forth the nature of the invention, what I claim herein is:

1. In a sewing machine, a frame including a bed and an overhanging head, stitch-forming de-.

vices, feeding mechanism including a feed-bar for advancing fabric past said stitch-forming devices, a stationary cutter-blade having formed therein a thread-receiving notchopening in the direction of feed and having on side thereof sharpened to provide a cutting edge, a movable cutter-blade carried by said'feed-bar and cooperating with the cutting edge of said stationary blade, and means for yieldingly maintaining the blades in cutting relation with each other.

2. In asewing machine, a frame including a bed and an overhanging head, stitch-forming devices, feeding mechanism including a feed-bar for advancing fabric past said stitch-forming devices,

' a stationary cutter-blade having formed in one advancing fabric past said stitchforming devices, a stationary cutter-blade having formed in one side thereof a thread-receving notch opening in the direction of feed'and having one side thereof sharpened to provide a cutting edge, a movable cutter-blade cooperating with the cutting edge of said stationary blade and supported by at least one pin arrangedior endwise movement in said feed-bar, and a spring acting between said movable blade and said feed-bar for yieldingly maintaining the blades in cutting relation with each other.

4. In a sewing machine, a frame including a bed and an overhanging head, stitch-forming de vices, feeding mechanism including a feed-bar for advancing fabric past said stitch-forming devices, a boss formed upon said feed-bar, a plurality of pins joumaled for endwise movement in said boss, a cutter-biade supported by said pins and adapted to partake of the movements of said feed-bar, a stationary cutter-blade cooperating with the cutter-blade carried by said feedbar, and a spring acting between said boss on the feed-bar and the cutter-blade carried by the feed-bar for yieldingly urging the cutter-blade in shearing relation with said stationary cutterblade.

5. In a sewing machine, a frame including a work-support and an overhanging head, stitchforming devices and work-feeding mechanism, a

ter-blade, and means for actuating said movable cutter-blade during operation of the machine.

6. In a sewing machine, a'frame including a .work-support and an overhanging head,stitchforming devices and work-feeding mechanism, a

movable cutter-blade located rearwardly of the stitch-forming devices, means for actuating said movable blade, and a stationary blade cooperating with said movable blade to provide a threadcutter, said stationary blade disposed so that its upper end projects above the level of the worksupport to provide a guard element extending in a direction away from the stitch-forming devices to protect the fabric being stitched from contact with said movable blade.

7. In a sewing machine the combination with a frame having a work-support, stitch-forming devices and work-feeding mechanism, of a thread-cutter comprising a movable blade, means for actuating said movable blade, and a stationary blade having a cutting edge cooperating with said movable blade, said stationary blade having its cutting edge bent toward themovable blade and its upperend disposed so that it projects above the level of the work-support to provide a guard element extending rearwardly in the direction of the normal feed of the work through the ma,-

chine to protect the fabric being stitched from contact with said movable blade.

.8. A thread-cutting device for a sewing machine having a feeding mechanism and a worksupport, comprising a stationary cutter-blade formed with athread-receiving notch opening in the direction of the normal feed of the work through the machine and having a portion thereof adapted to project above the level of the worksupport; said portion of the thread-ereceiving notch above the work-support being sharpened to provide a cutting edge,'and a movable cutterblade adapted to cooperate with the sharpened edge of said stationary blade for severing thread introduced into said thread-receiving notch and between said blades. x g

9. A thread-cutting device for a: sewing machine having a reciprocatory' needle, work-feed- 15 ing mechanism and a work-support, comprising a stationary cutter-blade formed with a threadreceiving notch opening in the direction of the normalfeed ofv thework through the machine and having a portion thereof adapted to project above the level of the work+support rearwardly of the needle, said portion; of the thread-receiving notch above the work-support. being sharpened to provide a cutting edge'which is bent to a position out of alinement with the remainder of the stationary blade, and a movable cutterblade adapted to cooperate with the cutting edge of said stationary blade forsevering thread introduced betweensaid blades.

' HANS HACKLANDER. 

